cabg

By: Mohammed A Rajab

Coronary Artery Bypass Graft

(CABG)

Aim of CABG

• Complete revascularization of myocardium; to:

Relieve symptoms (angina, heart failure). Improve quality of life. Increase life expectancy.

Anatomic Considerations

From surgical point of view, coronary system is divided into 4 parts: 1-Left main coronary artery.2-Left anterior descending artery (LAD) (and its diagonal branches).3-Left circumflex artery (and its marginal branches).4-Right coronary artery (and its posterior descending branch [PDA]).

Anatomic Considerations, cont.

• Left main disease: A significant lesion affecting the left main coronary artery, and this lesion affects blood flow to both left anterior descending artery and left circumflex artery.

• One-vessel disease: A significant lesion (or lesions) affecting one of the other three arteries or one of its large branches is consid-ered.

• Two-vessel disease and three-vessel disease: Significant le-sions affecting two arteries or three arteries, respectively.

Indications for CABG

1- Left main coronary artery stenosis: Stenosis >50%, as annual mortality 10-15%.

2- Left main equivalent: > 70% stenosis of proximal left anterior de-scending (LAD), and proximal circumflex artery (PCA).

Indications for CABG, cont.

3- Three vessel disease particularly in diabetics.4- One or two vessel disease with extensive my-ocardium at risk, & not suitable for Percutaneous transluminal coronary angioplasty (PTCA).5- Coronary occlusive complications during PTCA or other endovascular interventions.6- Surgery for life-threatening complications after acute MI, including VSD, ventricular free-wall rupture or acute MR.

Techniques for CABG

• The standard approach midline ster-notomy

1- On-pump CABG (traditional, conventional tech.)Arrested heart with cardioplegia, using Cardiopul-monary Bypass .

2- Off-pump coronary artery bypass (OPCAB) With a beating heart and without the use of car-diopulmonary bypass.

On-pump CABG

• Very low mortality and morbid-ity.

• Excellent results. • The most widely used technique

worldwide.

Off-pump coronary artery bypass (OPCAB)

• Newer technique with the pro-posed benefit of lower compli-cation rates.

• Highly specialized technique with good results in the hands of surgeons who perform this surgery regularly.

Choice between On & Off- pump CABG

• The 2 techniques seem equally effective.SO,

The choice of the procedure should de-pend on the surgeon preference perform-ing the procedure for a particular patient.

Operative Issues

• Isolated proximal disease in large coronary ar-teries >1.0 - 1.5 mm, is ideal for bypass surgery;

• Small, diffusely diseased coronary arteries are not suitable for bypass surgery

• Arteries with severe stenosis are bypassed, ex-cept those of small caliber < 1 mm in diameter.

Operative Issues, cont.

• Left ventricular function is an important deter-minant of outcome of all heart diseases Patients with severe LV dysfunction usually

have poor prognosis. Patients with severe LV dysfunction and easily

bypassable coronaries usually do very well Patients with bad ventricles and marginally

graftable coronary arteries are usually poor surgical candidates

Conduits for CABG

1- Left internal thoracic (mam-mary) artery (LITA, LIMA):• Gold standard for LAD.• excellent long term patency (90-

95% at 15 years).

Conduits for CABG cont.

1- LIMA should always be used unless: 1) Emergency operation with hemodynamic de-compensation. 2) History of chest wall radiation or radical mas-tectomy. 3)Proximal left subclavian artery stenosis.4) Iatrogenic injury or hematoma during harvest-ing.5) Insufficient flow due to small size or persistent spasm.

2- Reversed saphenous vein grafts (SVG) • Commonly used especially when many grafts.

such as triple or quadruple bypass are required.• Ten-year patency is 60-70%. • The causes of graft failure are:

Thrombosis. Intimal hyperplasia. Graft atherosclerosis.


3- Right internal thoracic (mammary) artery (RITA, RIMA) • Used in bilateral internal thoracic (mammary)

artery grafting• Patients receiving bilateral IMAs:

Less risk of recurrent angina, BUT with Higher rates of sternal infection, dehiscence and mediastinitis especially in elderly, obese or diabetic patients.


4-Radial artery • Approximately 85-90% patency at 5

years. • Prone to severe vasospasm P.O. due

to muscular wall; patients often placed on Calcium Channel Blockers.


5- Right gastroepiploic artery • Used as an in situ graft or as a free graft if no

alternative suitable conduit are available.• Infrequently used due to: The artery is fragile. Small diameter at the site of distal anasto-

mosis. Possibility of vessel twisting. Increased operative time (need laparotomy

incision).


cabg

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